1. Field of the Invention
This invention relates to 2'-deoxy-4'-thioribonucleosides and intermediates useful in their production, and to the use of 2'-deoxy-4'-thioribonucleosides as antiviral and anticancer agents.
A nucleoside is a molecule comprised of a pentose sugar in a furanose ring joined to a nitrogenous heterocyclic base that is a derivative of either purine or pyrimidine. A 4'-thionucleoside is a nucleoside wherein the furanose ring oxygen has been replaced by sulfur. A 2'-deoxy-4'-thioribonucleoside is a 4'-thionucleoside wherein the pentose sugar is 2'-deoxy-D-ribose.
As used herein, the terms "nucleoside", "4'-thionucleoside" and "2'-deoxy-4'-thioribonucleoside" shall also include compounds wherein the nitrogenous heterocyclic base is a base related to the purine and pyrimidine bases, but with a ring alteration, such nitrogenous heterocyclic bases including 3-deazapurines, 7-deazapurines, 8-azapurines, 2-azapurines, 5-azapyrimidines, 6-azapyrimidines, and 3-deazapyrimidines and shall also include compounds having acyl protecting groups at the 3' position, or the 5' position, or both, of the 2'-deoxy-D-ribose.
2. Description of the Related Art
Several 4'-thionucleosides have been reported in the literature. Reist, et al, J. Am. Chem. Soc., 86, 5658 (1964) disclose L and D forms of 4'-thioriboadenosine. Biological effects of 4'-thioriboadenosine are described in Miura, et al in Purine and Pyrimidine Metabolism in Man, V, Part B, (Plenum Publishing Corp., 1986) p. 667. Richie, et al, Can. J. Chem., 56, 794 (1977) disclose the synthesis of 9-(3-deoxy-4-thio-.beta.-D-erythro-pentofuranosyl)adenine (4'-thiocordycepin). Reist, et al, J. Org. Chem., 33, 189 (1968) describe the synthesis of adenine nucleosides of 4-thio-D-xylose and 4-thio-D-arabinose. Ototani, et al. J. Med. Chem., 17, 535 (1974) disclose the preparation and antitumor activity of 4'-thio-1-.beta.-D-arabinofuranosylcytosine and 2,2'-anhydro-4'-thio-1-.beta.-D-arabinofuranosylcytosine hydrochloride.
The description, preparation and use of specific 2'-deoxy-4'-thioribonucleosides is not found in the literature. Fu, et al, J. Org. Chem., 41, 3831 (1976) disclose a method for the preparation of anomeric methyl-2-deoxy-4-thio-D-erythro-pentofuranosides and suggest that the furanosides could be used as precursors for the synthesis of 2'-deoxy-4'-thionucleosides.